Reverse Lights on with Driving Lights


New member

I am new to Sprinter Vans and experiencing all the fun uniqueness of the machines!!! My Sprinter backup lights work perfect when the light switch in in the off position. At night when I turn the switch to one so I have dash lights I also have backup lights on full time. Is there another switch somewhere? I asume this is a feature for loading cargo at night but can not find anywhere to turn it off!

2005 Sprinter 140WB Mid height

Your thought are appreciated ... Thank-you


Sounds more like a short to me. This kind of funkery normally happens when the twin filament brake/running bulb is in backwards or a misfit; also happens if one of the plug sockets to the back of the rear light fittings is wrong way around or there's chaffing to the cabling.

Take out one or both of the twin filament brake/running bulbs. Does the weirdness stop?

Sent from my iPhone using Tapatalk Pro which means I am probably lying under the van wishing I had a crawler and a large warm workshop I could park in.


Erratic Member
Echoing Arnie_Oil, here's what could be happening:


Normally the tail light current flows through the light, thence to the frame.

But if the path to the frame is broken (and it can happen in the tail light assembly's soldered joints), then the current will follow whatever lowest-resistance path it can find to the frame... which may mean "through the reverse lights".

Adding to the confusion would be putting the combo tail/brake bulb in upside down, so that the low resistance filament is in the "tail light" position .... (that would also make stepping on the brakes produce a dimmer signal). That lower resistance means that more current would flow, which would provide more current to make the reverse lights brighter.

("upside down"? Look carefully at the base of a combo (dual-filament) bulb.... the two locking pins are slightly displaced to make it more difficult (but not impossible) to latch the bulb into position if you get it wrong)


Last edited:


New member
Hello Gentlemen ... still working through resolving the issue. I checked to ensure the bulbs were correct and installed properly. At this time I have removed the reverse bulb, it no longer lights up with the running lights are turned on ... problem solved!!! hahaha

Aqua Puttana

Poly - Thread Finder
Position 1... ?
Have you tried the headlight positions?

I didn't notice a geographic location.

There is a rear fog light feature available for Euro Sprinters.

Are you confusing rear fog lights for reverse?

Have the rear tail light assemblies been replaced? Maybe they are a different style.

:cheers: vic

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